Digestion and the digestive system

• Digestion


  The process by which food is broken down into smaller molecules that can be absorbed by the body.
• the digestion of larger insoluble molecules into their soluble products which can be absorbed


  Fats - made up of fatty acids and glycerol

  Proteins - Made up of amino acids

  Carbohydrates - Made up of simple sugars e.g starch made from glucose
• Test for presence of starch, glucose and protein

  Starch - Iodine solution

  Glucose - Benedicts solution

  Protein - Biuret solution
• Role of carbohydrase, lipases, and proteases

  Carbohydrase's - Catalase breakdown of carbohydrase into simple sugars

  Lipases - Catalase breakdown of fats into glycerol and fatty acids Proteases - Catalase breakdown of proteins into amino acids
• Function of mouth


  Food is chewed into smaller pieces Amylase in saliva breaks starch to maltose
• Function of stomach


  Secretes protease which breaks down proteins

  Contains hydrochloric acid which kills any bacteria in food
• Function of pancreas


  Secretes carbohydrase and lipase (transported to small intestine)
• Function of small intestine

  Carbohydrase breaks down carbohydrates

  Protease breaks down proteins

  Lipases breaks down lipids

  Food molecules are absorbed into bloodstream
• Function of large intestine

  Reabsorbs water into bloodstream
• Function of liver


  Produces bile
• How does peristalsis move food

  It is a wave of muscle contractions in the gut which forces food down the gut
• Function of bile


  Secreted by the liver and stored in the gall bladder in breakdown of fats
• What can be a model for the gut

  Visking tube
• The fate of the digested products of fats, carbohydrates and proteins provide energy

  Fatty acids and glycerol from fats provide energy

  Glucose from carbohydrates provide energy or is stored as glycogen Amino acids from digested proteins are needed to build proteins in the body
• Why is protein needed for a balanced diet

  Broken in to amino acids

  Joined in long chains to form new proteins which are used for growth
• Why is carbohydrates needed for a balanced diet

  Broken into smaller sugars e.g. glucose

  Sugars used in respiration to release energy or are stored
• Why is vitamins needed for a balanced diet

  Vitamin C involved in collagen and working of immune system
• Why is fiber needed for a balanced diet

  Provides bulk which aids movement of food via peristalsis
• Why is water needed for a balanced diet

  Enables chemical reactions to happen

  Main component of cells
• Why is too much sugar, fat and salt bad

  Sugar - Risk of obesity, type 2 diabetes, tooth decay

  Fat - Risk of obesity, cardiovascular disease, type 2 diabetes, cancer

  Salt - Risk of high blood pressure, cardiovascular disease
• Why do we need to digest large food molecules

  Its small enough to absrob
• Explain effect on bile on rate of digestion of lipids

  Bile emulsifies fat and bile creates a larger surface area for lipids to work
• Where is bile made

  Liver
• Where is bile stored

  Gall bladder